U.S. patent number 6,865,796 [Application Number 09/711,073] was granted by the patent office on 2005-03-15 for method of manufacturing a stator for an alternator with reduced conductor portions.
This patent grant is currently assigned to Mitsubishi Denki Kabushiki Kaisha. Invention is credited to Katsumi Adachi, Yoshihito Asao, Atsushi Oohashi, Takushi Takizawa.
United States Patent |
6,865,796 |
Oohashi , et al. |
March 15, 2005 |
Method of manufacturing a stator for an alternator with reduced
conductor portions
Abstract
Coil members are obtained by forming width-reduced portions in a
wire material over a predetermined longitudinal range generally
centered on cutting positions, then removing an insulation coating
from the width-reduced portions, and thereafter cutting the wire
material at the width-reduced portions. Coil segments are prepared
by bending the coil members into a general U shape. Then the coil
segments are inserted into the slots in a stator core, and a stator
is obtained by welding together the free end portions of the
projecting coil segments.
Inventors: |
Oohashi; Atsushi (Tokyo,
JP), Asao; Yoshihito (Tokyo, JP), Adachi;
Katsumi (Tokyo, JP), Takizawa; Takushi (Tokyo,
JP) |
Assignee: |
Mitsubishi Denki Kabushiki
Kaisha (Tokyo, JP)
|
Family
ID: |
18568645 |
Appl.
No.: |
09/711,073 |
Filed: |
November 14, 2000 |
Foreign Application Priority Data
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Feb 23, 2000 [JP] |
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2000-046175 |
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Current U.S.
Class: |
29/596; 242/432;
29/732; 310/215; 29/605 |
Current CPC
Class: |
H02K
3/12 (20130101); H02K 15/0056 (20130101); H02K
15/064 (20130101); H02K 15/0478 (20130101); H02K
15/0081 (20130101); H02K 15/066 (20130101); Y10T
29/49071 (20150115); Y10T 29/49009 (20150115); Y10T
29/53143 (20150115) |
Current International
Class: |
H02K
15/00 (20060101); H02K 15/06 (20060101); H02K
15/04 (20060101); H02K 3/12 (20060101); H02K
015/00 (); H02K 003/34 () |
Field of
Search: |
;29/596,598,592.1,825,867,564.4,605,732 ;310/179,180,201,198,215
;81/9.51,9.4 ;242/432 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1 265 020 |
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Jun 1961 |
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FR |
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6-141496 |
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May 1994 |
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JP |
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7-44797 |
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May 1995 |
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JP |
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11-341730 |
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Dec 1999 |
|
JP |
|
Other References
Patent Abstracts of Japan vol. 3, No. 60 (E-112), May 23,
1979-& JP 54-38501 A (Hitachi LTD), Mar. 23, 1979. .
Patent Abstracts of Japan vol. 4, No. 52 (E-7), Apr. 18, 1980-&
JP 55-023773 A (Hitachi LTD), Feb. 20, 1980..
|
Primary Examiner: Jimenez; Marc
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. A method for manufacturing a stator for an alternator,
comprising: providing a conductor comprising a flat electrically
conductive material and an insulation coating, the insulation
coating covering an outer surface of the electrically conductive
material; forming one or more reduced outer portions of the
conductor by removing, from respective predetermined longitudinal
sections of the conductor, the insulation coating and a
corresponding portion of the electrically conductive material;
forming coil members by cutting the conductor at cutting positions
located within the predetermined longitudinal sections; forming
coil wires of a predetermined shape by subjecting said coil members
to a bending process; installing a predetermined number of said
coil wires in a stator core; and forming a winding group having a
predetermined number of turns by welding together end portions of
each of said coil wires installed in said stator core.
2. The method for manufacturing a stator for an alternator
according to claim 1, wherein said forming the one or more reduced
outer portions comprises: forming a width-reduced portion by
removing first and second edges of said electrically conductive
material in a width direction together with said insulation coating
over said predetermined longitudinal sections; and removing said
insulation coating from first and second edges of said
width-reduced portion in a thickness direction.
3. The method for manufacturing a stator for an alternator
according to claim 2 wherein said width-reduced portion is formed
by cutting away said first and second edges of said electrically
conductive material in said width direction together with said
insulation coating by a machining process.
4. The method for manufacturing a stator for an alternator
according to claim 2 wherein said width-reduced portion is formed
by cutting off said first and second edges of said electrically
conductive material in said width direction together with said
insulation coating using a press-cutting method.
5. The method for manufacturing a stator for an alternator
according to claim 2 wherein said width-reduced portion is formed
by: forming a thickness-reduced portion over a predetermined
longitudinal range generally centered on each of said cutting
positions by rolling said wire material; and then cutting off said
first and second edges of said electrical conductor in said width
direction together with said insulation coating at said
thickness-reduced portion using a press-cutting method.
6. The method for manufacturing a stator for an alternator
according to claim 2 wherein said width-reduced portion is formed
into a shape having a cross section tapering towards a central
portion from first and second longitudinal ends.
7. The method for manufacturing a stator for an alternator
according to claim 2 wherein said insulation coating on said
reduced outer portion is removed by a machining process.
8. The method for manufacturing a stator for an alternator
according to claim 2 wherein said insulation coating on said
reduced outer portion is burned away by a flame and then carbides
formed thereby are removed by brushing.
9. The method for manufacturing a stator for an alternator
according to claim 2 wherein said insulation coating on said
reduced outer portion is removed by burning away by means of
irradiation with a laser.
10. The method for manufacturing a stator for an alternator
according to claim 2 wherein said insulation coating on said
reduced outer portion is removed by dissolution with a solvent.
11. The method for manufacturing a stator for an alternator
according to claim 2 further comprising forming a smooth tip shape
by melting corner portions of first and second ends of said coil
members or said coil wires.
12. The method for manufacturing a stator for an alternator
according to claim 1 wherein said forming one or more reduced outer
portions comprises: forming a width-reduced portion by forming said
conductor into a round shape of circular cross section over said
predetermined longitudinal sections centered on each of said
cutting positions; and removing said insulation coating of said
width-reduced portion by mechanical stripping.
13. The method for manufacturing a stator for an alternator
according to claim 12 further comprising forming said width-reduced
portion from which said insulation coating has been mechanically
stripped into a flat shape.
14. The method for manufacturing a stator for an alternator
according to claim 1 wherein said coil wires are formed into a
general U shape composed of a pair of straight portions separated
by a predetermined number of slots being connected by a turn
portion having a general V shape.
15. The method for manufacturing a stator for an alternator
according to claim 1 wherein said coil wires are formed into a
wave-shaped continuous wire in which straight portions are arranged
at a predetermined slot pitch and end portions of adjacent straight
portions are connected to each other by generally V-shaped turn
portions.
16. The method for manufacturing a stator for an alternator
according to claim 1, wherein the cutting of the conductor at the
cutting positions is performed after the reduced outer portions of
the conductor are formed and the conductor is cut at the reduced
outer portion of the conductor.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a stator for an alternator driven
by an internal combustion engine, for example, and to a method for
manufacturing the stator, and in particular, relates to a stator
for an alternator and a method for the manufacture thereof in which
the stator is provided with a stator coil constructed by installing
coil wires having a flat cross section formed into a predetermined
shape into a stator core, and welding together end portions of the
coil wires.
2. Description of the Related Art
FIG. 38 is a cross section showing the construction of a generic
alternator.
The conventional alternator includes: a Lundell-type rotor 7
mounted so as to rotate freely by means of a shaft 6 within a case
3 composed of an aluminum front bracket 1 and an aluminum rear
bracket 2; and a stator 8 secured to the inner wall of the case 3
so as to cover the outer circumference of the rotor 7.
The shaft 6 is rotatably supported by the front bracket 1 and the
rear bracket 2. A pulley 4 is secured to one end of the shaft 6 to
enable rotational torque from an engine to be transmitted to the
shaft 6 by means of a belt (not shown).
Slip rings 9 for supplying electric current to the rotor 7 are
secured to the other end of the shaft 6, and a pair of brushes 10
are housed in a brush holder 11 and disposed within the case 3 so
as to slide in contact with the slip rings 9. A regulator 18 for
regulating the magnitude of an alternating voltage generated in the
stator 8 is affixed by adhesive to a heat sink 17 attached to the
brush holder 11. A rectifier 12 electrically connected to the
stator 8 for converting the alternating voltage generated in the
stator 8 into direct current is mounted within the case 3.
The rotor 7 includes: a rotor coil 13 for conducting electric
current and generating magnetic flux; and a pair of pole cores 20,
21 disposed so as to cover the rotor coil 13, magnetic poles being
formed in the pair of pole cores 20, 21 by the magnetic flux
generated by the rotor coil 13. The pair of pole cores 20, 21 are
made of iron, each has a plurality of claw-shaped magnetic poles
22, 23 projecting from an outer circumferential edge thereof spaced
at even angular pitch circumferentially, and the pole cores 20, 21
are secured to the shaft 6 facing each other so that the
claw-shaped magnetic poles 22, 23 intermesh. In addition, fans 5
are secured to both axial ends of the rotor 7.
The stator 8 includes: a stator core 15; and a stator coil 16
composed of wire wound around the stator core 15 and having coil
end groups 16a and 16b extending from the axial ends of the stator
core 15.
In an alternator constructed in this manner, current is supplied to
the rotor coil 13 from a battery (not shown) by means of the
brushes 10 and the slip rings 9, and magnetic flux is generated.
The claw-shaped magnetic poles 22 of one pole core 20 are polarized
with north-seeking (N) poles by the magnetic flux, and the
claw-shaped magnetic poles 23 of the other pole core 21 are
polarized with south-seeking (S) poles. At the same time, the
rotational torque of the engine is transmitted to the shaft 6 by
means of the belt and the pulley 4, and the rotor 7 is rotated.
Thus, a rotating magnetic field is imparted to the stator coil 16
and electromotive force is generated in the stator coil 16. This
alternating electromotive force is converted into direct current by
means of the rectifier 12, its magnitude is regulated by the
regulator 18, and the battery is recharged.
Next, the construction of a conventional stator 8 will be explained
in detail with reference to FIGS. 39 and 40. FIG. 39 is a
perspective showing a coil segment constituting part of a
conventional stator coil, and FIG. 40 is a perspective of part of a
conventional stator viewed from the front end.
As shown in FIG. 39, the coil segments 30 functioning as coil wires
are formed into a predetermined shape by cutting insulated copper
wire material having a flat cross section into predetermined
lengths which constitute coil members 29 and applying a bending
process to the short, cut coil members 29. More specifically, the
coil segments 30 are composed of a pair of straight portions 30a in
which the longitudinal direction of the cross sections of each are
generally parallel to each other, and a turn portion 30b which
connects the straight portions 30a in a general V shape in which
the longitudinal direction of the cross section is twisted at
approximately 180.degree. at an apex portion, forming an overall U
shape.
In FIG. 40, the stator core 15 is formed into a cylindrical shape,
a number of teeth 15a having a generally rectangular
cross-sectional shape are disposed at even angular pitch
circumferentially so as to extend radially inwards, and slots 15b
for housing the coil are formed between the teeth 15a. The grooves
of the slots 15b are parallel to an axial direction and are open on
an inner circumferential side. Insulating paper 19 is housed in
each of the slots 15a. In this case, the rotor has 12 poles, and
the stator 8 has thirty-six slots 15b, making the number of slots
per pole per phase equal to one.
These coil segments 30 are inserted two at a time from a rear end
of the stator core 15 into pairs of slots 15b three slots apart
such that the height of the turn portions 30b is uniform. Thus,
four straight portions 30a are housed in each of the slots 15b such
that the longitudinal direction of the cross sections of the
straight portions 30a are aligned in a radial direction so that the
straight portions 30a line up in a row radially. Free end portions
30c of the coil segments 30 projecting from each of the slots 15b
are each bent circumferentially in the vicinity of the end of the
stator core 15, then the free end portions 30c are each
additionally bent such that the longitudinal direction of the cross
sections thereof are each aligned radially and the free end
portions 30c are parallel to the axial direction. The free end
portions 30c of coil segments 30 projecting from slots 15b three
slots apart are stacked radially and welded together, constituting
three winding phase groups having four turns in each phase. The
stator coil 16 is prepared by connecting the three winding phase
groups constructed in this manner into a Y connection, for
example.
The turn portions 30b of the coil segments 30 in the rear-end coil
end group 16b of the stator coil 16 are constructed so as to be
arranged circumferentially so as to line up radially in two rows at
the rear end of the stator core 15. On the other hand, the
front-end coil end group 16a is constructed such that inner
circumferential joint portions 31 formed by radially stacking and
welding the free end portions 30c of the coil segments 30
projecting from the first position (hereinafter called the first
address) from the inner circumferential side of the slots 15b and
the free end portions 30c of the coil segments 30 projecting from
the second position (hereinafter called the second address) from
the inner circumferential side of the slots 15b three slots away,
and outer circumferential joint portions 32 formed by radially
stacking and welding the free end portions 30c of the coil segments
30 projecting from the third position (hereinafter called the third
address) from the inner circumferential side of the slots 15b and
the free end portions 30c of the coil segments 30 projecting from
the fourth position (hereinafter called the fourth address) from
the inner circumferential side of the slots 15b three slots away
are arranged circumferentially so as to line up radially in two
rows.
A method for manufacturing the conventional stator 8 will now be
explained with reference to FIGS. 41 to 48.
First, flat insulated copper wire material is cut into
predetermined lengths using a nipper or the like to obtain coil
members 29, as shown in FIG. 41.
Then, coil segments 30 functioning as coil wires shown in FIG. 42
are obtained by forming a coil member 29 into a U shape by a
bending process.
Then, the coil segments 30 are inserted two at a time into pairs of
slots 15b three slots apart such that the height of the turn
portions 30b is uniform. At this time, four straight portions 30a
are housed in each slot 15b such that the longitudinal direction of
the cross sections of the straight portions 30a are aligned in the
radial direction so as to line up in a row radially. The free end
portions 30c of the coil segments 30 projecting from each of the
slots 15b are each bent circumferentially in the vicinity of the
end of the stator core 15, then the free end portions 30c are each
additionally bent such that the longitudinal direction of the cross
sections thereof are each aligned radially and the free end
portions 30c are parallel to the axial direction. Thus, the free
end portions 30c of the two coil segments 30 projecting from the
first and third addresses from the inner circumferential side of a
slot 15b and the free end portions 30c of the two coil segments 30
projecting from the second and fourth addresses from the inner
circumferential side of a slot 15b three slots away are lined up in
the radial direction as shown in FIGS. 43 and 44.
Next, the ends of the four coil segments 30 are held by lining up
clamping jigs 27 in a straight line and bringing the tips of the
jigs 27 together, as shown in FIGS. 45 and 46. Then, the free end
portions 30c of the two coil segments 30 on the inner
circumferential side are fused and joined together by
tungsten-inert gas (TIG) welding using an arc. The free end
portions 30c of the two coil segments 30 on the outer
circumferential side are fused and joined together in the same way
by TIG welding using an arc. Thus, inner circumferential joint
portions 31 and outer circumferential joint portions 32 are
obtained as shown in FIGS. 47 and 48. The three winding phase
groups having four turns in each phase are obtained by welding each
of the free end portions 30c together. Moreover, heat generated
during welding is transferred through the jigs 27 to a radiating
jig 28 and radiated to prevent the coating on the coil segments 30
from being burned.
The stator coil 16 is prepared by connecting the three winding
phase groups prepared in this manner into a Y connection, for
example.
In this conventional stator for an alternator, short coil members
29 obtained by cutting wire material using a nipper or the like,
are formed into U-shaped coil segments 30 by a bending process. As
shown in FIG. 41, bulges A and burrs B caused by cutting arise on
side portions of the cross sections of these coil members 29.
Because the bulges A and burrs B extend beyond the profile of the
coil members 29, when the coil segments 30 are being inserted into
the slots 15b, the bulges A catch and make it difficult to insert
the coil into the slots, and the burrs B damage the insulating
paper 19 giving rise to insulation defects. Thus, one problem has
been reduced productivity and reliability.
Because the insulation coating on the free end portions 30c of the
coil segments 30 is not removed, welding deteriorates, giving rise
to dislodgement of the joint portions due to vibrations from the
engine, etc., causing problems which reduce reliability.
Because the outer dimension of the free end portions 30c of the
coil segments 30 is not reduced, the free end portions 30c which
are joined in the coil end group 16a are arranged in close contact
in one row radially, leaving little space for welding. As a result,
when welding the free end portions 30c of the two coil segments 30
on the inner circumferential side, for example, there is a risk
that the heat of welding will be transferred to the free end
portions 30c of the coil segments 30 on the outer circumferential
side and weld them to the free end portions 30c on the outer
circumferential side as well, reducing productivity. In addition,
because it is difficult to concentrate the arc on the interface
between the free end portions 30c of the two coil segments 30 being
welded and the fused surface area is reduced, sufficient weld
strength cannot be obtained, giving rise to dislodgment of the
joint portions due to vibrations from the engine, etc., thus
causing problems which reduce reliability. Furthermore, electrical
resistance is increased in the joint portions, increasing the
amount of heat generated by the output current during power
generation, causing reduced output due to temperature
increases.
Furthermore, if welding time is increased in order to ensure
sufficient fused surface area, the weld bead formed on the joint
portion becomes too large, which later results in the occurrence of
layer shorts due to vibration, thus reducing reliability.
SUMMARY OF THE INVENTION
The present invention aims to solve the above problems, and an
object of the present invention is to provide a stator for an
alternator and a method of manufacturing the stator enabling the
achievement of increased reliability, and improved productivity by
forming coil members by forming a reduced outer portion and then
cutting the wire material at the reduced outer portion.
In order to achieve the above object, according to one aspect of
the present invention, there is provided a method for manufacturing
a stator for an alternator, the method including:
forming coil members by cutting wire material into predetermined
lengths, the wire material being composed of an electrical
conductor having a flat cross section coated with an insulation
coating;
forming coil wires of a predetermined shape by subjecting the coil
members to a bending process;
installing a predetermined number of the coil wires into a stator
core; and
forming a winding group having a predetermined number of turns by
welding together end portions of each of the coil wires installed
in the stator core,
the method further including:
forming a reduced outer portion over a predetermined longitudinal
range generally centered on each of the cutting positions on the
wire material.
According to another aspect of the present invention, there is
provided a stator for an alternator, the stator including:
a cylindrical stator core in which a number of slots having grooves
aligned axially are disposed parallel to each other
circumferentially so as to be open on an inner circumferential
side; and
a stator coil constructed by welding together a number of end
portions of coil wires having a flat cross section coated with an
insulation coating, the stator coil being wound so as to fold back
outside the slots at axial end surfaces of the stator core so as to
alternately occupy an inner and an outer layer in a slot depth
direction within the slots at intervals of a predetermined number
of slots,
wherein an outer dimension of each of the end portions of the coil
wires is reduced compared to other portions of the coil wire.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective showing wire material used in a stator coil
of a stator for an alternator according to Embodiment 1 of the
present invention;
FIG. 2 is a cross section taken along line II--II in FIG. 1;
FIG. 3 is a perspective showing reduced outer portions formed in
the wire material in a method for manufacturing the stator for an
alternator according to Embodiment 1 of the present invention;
FIG. 4 is a cross section taken along line IV--IV in FIG. 3;
FIG. 5 is an enlarged view of portion A in FIG. 4;
FIG. 6 is a perspective showing coil members formed by cutting the
wire material in the method for manufacturing the stator for an
alternator according to Embodiment 1 of the present invention;
FIG. 7 is a perspective showing a coil segment formed by applying a
bending process to a coil member in the method for manufacturing
the stator for an alternator according to Embodiment 1 of the
present invention;
FIG. 8 is an end elevation explaining the arrangement of free end
portions of coil segments inserted into a stator core in the method
for manufacturing the stator for an alternator according to
Embodiment 1 of the present invention;
FIG. 9 is a side elevation explaining the arrangement of free end
portions of coil segments inserted into the stator core in the
method for manufacturing the stator for an alternator according to
Embodiment 1 of the present invention;
FIG. 10 is an end elevation explaining welding of the free end
portions of coil segments in the method for manufacturing the
stator for an alternator according to Embodiment 1 of the present
invention;
FIG. 11 is a side elevation explaining welding of the free end
portions of coil segments in the method for manufacturing the
stator for an alternator according to Embodiment 1 of the present
invention;
FIG. 12 is an end elevation explaining the welded state of the free
end portions of coil segments in the method for manufacturing the
stator for an alternator according to Embodiment 1 of the present
invention;
FIG. 13 is a side elevation explaining the welded state of the free
end portions of coil segments in the method for manufacturing the
stator for an alternator according to Embodiment 1 of the present
invention;
FIG. 14 is a perspective showing part of a front end of the stator
manufactured by the method for manufacturing the stator for an
alternator according to Embodiment 1 of the present invention;
FIG. 15 is a perspective showing width-reduced portions formed in
wire material in a method for manufacturing a stator for an
alternator according to Embodiment 2 of the present invention;
FIG. 16 is a cross section taken along line XVI--XVI in FIG.
15;
FIG. 17 is a perspective showing width-reduced portions of the wire
material with insulation coating removed in the method for
manufacturing the stator for an alternator according to Embodiment
2 of the present invention;
FIG. 18 is a perspective showing thickness-reduced portions formed
in wire material in a method for manufacturing a stator for an
alternator according to Embodiment 6 of the present invention;
FIG. 19 is a cross section taken along line XIX--XIX in FIG.
18;
FIG. 20 is a perspective showing width-reduced portions formed in
wire material in a method for manufacturing the stator for an
alternator according to Embodiment 6 of the present invention;
FIG. 21 is a cross section taken along line XXI--XXI in FIG.
20;
FIG. 22 is a perspective showing width-reduced portions formed in
wire material in a method for manufacturing a stator for an
alternator according to Embodiment 7 of the present invention;
FIG. 23 is a perspective showing width-reduced portions formed in
wire material in a method for manufacturing a stator for an
alternator according to Embodiment 8 of the present invention;
FIG. 24 is a cross section taken along line XXIV--XXIV in FIG.
23;
FIG. 25 is a diagram explaining removal of insulation coating from
width-reduced portions of wire material in the method for
manufacturing the stator for an alternator according to Embodiment
8 of the present invention;
FIG. 26 is a perspective showing width-reduced portions formed in
wire material in a method for manufacturing a stator for an
alternator according to Embodiment 9 of the present invention;
FIG. 27 is a cross section taken along line XXVII--XXVII in FIG.
26;
FIG. 28 is a perspective showing parts of coil members in a method
for manufacturing a stator for an alternator according to
Embodiment 10 of the present invention;
FIG. 29 is an end elevation explaining connections in one stator
coil phase group in the stator for an alternator according to
Embodiment 11 of the present invention;
FIG. 30 is a circuit diagram for the stator for an alternator
according to Embodiment 11 of the present invention;
FIG. 31 is a diagram explaining the manufacturing process for
coil-wire groups constituting part of a stator coil in the stator
for an alternator according to Embodiment 11 of the present
invention;
FIG. 32 is a diagram explaining the manufacturing process for
coil-wire groups constituting part of the stator coil in the stator
for an alternator according to Embodiment 11 of the present
invention;
FIG. 33A is an end elevation showing a winding assembly
constituting part of the stator coil in the stator for an
alternator according to Embodiment 11 of the present invention;
FIG. 33B is a front elevation showing the winding assembly
constituting part of the stator coil in the stator for an
alternator according to Embodiment 11 of the present invention;
FIG. 34 is a perspective showing part of a strand of coil wire
constituting part of the stator coil in the stator for an
alternator according to Embodiment 11 of the present invention;
FIG. 35 is a diagram explaining the arrangement of strands of coil
wire constituting part of the stator coil in the stator for an
alternator according to Embodiment 11 of the present invention;
FIG. 36 is a diagram explaining the construction of a laminated
core constituting the stator core in the stator for an alternator
according to Embodiment 11 of the present invention;
FIG. 37A is a cross section explaining the manufacturing process
for the stator in the stator for an alternator according to
Embodiment 11 of the present invention;
FIG. 37B is a cross section explaining the manufacturing process
for the stator in the stator for an alternator according to
Embodiment 11 of the present invention;
FIG. 37C is a cross section explaining the manufacturing process
for the stator in the stator for an alternator according to
Embodiment 11 of the present invention;
FIG. 38 is a cross section showing a generic alternator;
FIG. 39 is a plan showing a coil segment in a conventional
stator;
FIG. 40 is a perspective of part of the conventional stator viewed
from the front end;
FIG. 41 is a perspective showing coil members formed by cutting
wire material in a conventional method for manufacturing a stator
for an alternator;
FIG. 42 is a plan showing a coil segment formed by applying a
bending process to a coil member in the conventional method for
manufacturing a stator for an alternator;
FIG. 43 is an end elevation explaining arrangement of free end
portions of coil segments inserted into a stator core in the
conventional method for manufacturing a stator for an
alternator;
FIG. 44 is a side elevation explaining the arrangement of the free
end portions of coil segments inserted into a stator core in the
conventional method for manufacturing a stator for an
alternator;
FIG. 45 is an end elevation explaining welding of the free end
portions of coil segments in the conventional method for
manufacturing a stator for an alternator;
FIG. 46 is a side elevation explaining welding of the free end
portions of coil segments in the conventional method for
manufacturing a stator for an alternator;
FIG. 47 is an end elevation explaining the welded state of the free
end portions of coil segments in the conventional method for
manufacturing a stator for an alternator; and
FIG. 48 is a side elevation explaining the welded state of the free
end portions of coil segments in the conventional method for
manufacturing a stator for an alternator.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred embodiments of the present invention will now be
explained with reference to the drawings.
Embodiment 1
FIG. 1 is a perspective showing wire material used in a stator coil
of a stator for an alternator according to Embodiment 1 of the
present invention, FIG. 2 is a cross section taken along line
II--II in FIG. 1, FIG. 3 is a perspective showing reduced outer
portions formed in the wire material in a method for manufacturing
the stator for an alternator according to Embodiment 1 of the
present invention, FIG. 4 is a cross section taken along line
IV--IV in FIG. 3, FIG. 5 is an enlargement of portion A in FIG. 4,
FIG. 6 is a perspective showing coil members formed by cutting the
wire material in the method for manufacturing the stator for an
alternator according to Embodiment 1 of the present invention, FIG.
7 is a perspective showing a coil segment formed by applying a
bending process to a coil member in the method for manufacturing
the stator for an alternator according to Embodiment 1 of the
present invention, FIGS. 8 and 9 are an end elevation and a side
elevation, respectively, explaining the arrangement of free end
portions of coil segments inserted into a stator core in the method
for manufacturing the stator for an alternator according to
Embodiment 1 of the present invention, FIGS. 10 and 11 are an end
elevation and a side elevation, respectively, explaining welding of
the free end portions of coil segments in the method for
manufacturing the stator for an alternator according to Embodiment
1 of the present invention, FIGS. 12 and 13 are an end elevation
and a side elevation, respectively, explaining the welded state of
free end portions of coil segments in the method for manufacturing
the stator for an alternator according to Embodiment 1 of the
present invention, and FIG. 14 is a perspective showing part of a
front end of the stator manufactured by the method for
manufacturing the stator for an alternator according to Embodiment
1 of the present invention.
The method for manufacturing a stator according to Embodiment 1
will now be explained with reference to FIGS. 1 to 13.
First, as shown in FIGS. 1 and 2, a wire material 40 is prepared by
coating a flat electrical conductor 39 made of copper or the like
having a rectangular cross section with an insulation coating 41.
For example, a wire material 40 in which the width of the
electrical conductor 39 is 2.5 mm, the thickness is 1.5 mm, the
thickness of the insulation coating 41 is 0.4 mm, and the radius of
curvature (R) of the corners is 0.4 mm can be used.
Then, by a machining process, both surfaces in a width direction of
the wire material 40 and both surfaces in a thickness direction
thereof are removed by machining to a machined depth (D) over a
predetermined range in a longitudinal direction at predetermined
distances along the wire material 40. Thus, a portion of the
electrical conductor 39 on both sides of the wire material 40 in
both the width and thickness directions is removed together with
the insulation coating 41, and a reduced outer portion 42 is
obtained as shown in FIGS. 3 and 4. As shown in FIG. 5, the
machined depth (D) is the minimum depth at which the insulation
coating 41 on the corners is removed, and is determined by the
insulation coating thickness (.delta.) and the radius of curvature
(R) of the corners, being given by D=R-(R-.delta.)/2.sup.1/2.In
this example, the machined depth (D) is 0.145 mm.
Next, the wire material 40 is cut at the longitudinal center of
each of the reduced outer portions 42 to obtain coil members 44
having a predetermined length. As shown in FIG. 6, the width and
thickness of both ends of these coil members 44 are narrow and the
insulation coating 41 has been removed from both ends to form weld
portions 45.
Coil segments 50, which function as coil wires, are obtained by
further applying a bending process to add twists to the coil
members 44. As shown in FIG. 7, the coil segments 50 are formed in
a general U shape having a pair of straight portions 50a connected
by a generally V-shaped turn portion 50b. The weld portions 45 of
the coil members 44 constitute free end portions 50c of the coil
segments 50. Moreover, the coil segments 50 are constructed in the
same way as the coil segments 30 shown in FIG. 39 except for the
fact that the free end portions 50c (the weld portions 45) are
formed with a narrow width and thickness.
Then, the coil segments 50 are inserted two at a time into pair of
slots 15b separated by three slots such that the heights of the
turn portions 50b are uniform. Here, four straight portions 50a are
housed in each slot 15b such that the longitudinal direction of the
cross sections of the straight portions 50a are aligned in the
radial direction so as to line up in a row radially. Then, the free
end portion sides of the coil segments 50 projecting from each of
the slots 15b are each bent circumferentially in the vicinity of
the end of the stator core 15, and the free end portions 50c are
each additionally bent such that the longitudinal direction of the
cross sections thereof are each aligned and the free end portions
50c are parallel to the axial direction. Thus, the two free end
portions 50c of coil segments 50 projecting from the first and
third addresses of a first slot 15b and the two free end portions
50c of coil segments 50 projecting from the second and fourth
addresses of a second slot 15b three slots away are lined up in the
radial direction as shown in FIGS. 8 and 9.
Next, the ends of the four coil segments 50 are held by lining up
clamping jigs 27 in a straight line and bringing the tips of the
jigs 27 together, as shown in FIGS. 10 and 11. Then, the free end
portions 50c of the two coil segments 50 on the inner
circumferential side are fused and joined by TIG welding using an
arc. The free end portions 50c of the two coil segments 50 on the
outer circumferential side are fused and joined in the same way by
TIG welding using an arc. Thus, as shown in FIGS. 12 and 13, inner
circumferential weld portions 51 and outer circumferential weld
portions 52 are obtained. Three winding phase groups having four
turns in each phase are obtained by welding each of the free end
portions 50c. In addition, the winding phase groups are connected
in a Y-connection, for example, to form a stator coil 61. Thus, a
stator 60 is obtained having the stator coil 61 wound onto the
stator core 15 as shown in FIG. 14.
The stator coil 61 constructed in this manner is wound into the
stator core 15 in a wave winding by welding together the free end
portions 50c of a large number of coil segments 50 so as to
alternately occupy an inner and an outer layer in a slot depth
direction within every third slot 15b. Although not shown, the turn
portions 50b of the coil segments 50 in the rear-end coil end group
of the stator coil 61 constructed in this manner are constructed so
as to be aligned in the circumferential direction in two lines
radially at the rear end of the stator core 15. On the other hand,
the front-end coil end group 61a is constructed such that inner
circumferential joint portions 51 formed by radially stacking and
welding the free end portions 50c of the coil segments 50
projecting from the first address of first slots 15b and the free
end portions 50c of the coil segments 50 projecting from the second
addresses of second slots 15b three slots away, and outer
circumferential joint portions 52 formed by radially stacking and
welding the free end portions 50c of the coil segments 50
projecting from the third addresses of first slots 15b and the free
end portions 50c of the coil segments 50 projecting from the fourth
addresses of second slots 15b three slots away are arranged
circumferentially so as to line up in two rows radially.
The stator 60 prepared in this manner is mounted in an alternator
in place of the conventional stator 8 and operates in the same
way.
According to Embodiment 1 of the present invention, because reduced
outer portions 42 are formed in the wire material 40 and then the
wire material 40 is cut at the reduced outer portions 42 to obtain
the coil members 44, any bulges and burrs arising on side portions
of the cut sections of the reduced outer portions 42 have a smaller
profile than the outer dimension of the wire material 40. Thus,
when the coil segments 50 are being inserted into the slots 15b,
the bulges and burrs are prevented from interfering with the slots
15b or damaging the insulating paper 19. Insertion of the coil into
the slots is thereby improved and the occurrence of insulation
defects is suppressed, enabling productivity and reliability to be
improved.
Because the electrical conductor 39 on both sides of the wire
material 40 in the width direction is cut away together with the
insulation coating 41 by the machining process to form the
width-reduced portions, the surface area over which the insulation
coating 41 must be removed is reduced, enabling the time required
for removing the insulation coating 41 to be shortened.
Furthermore, because the insulation coating 41 is removed from the
upper and lower surfaces of the width-reduced portions (both
surfaces in a thickness direction) by applying the machining
process, the formation of the width-reduced portions and the
removal of the insulation coating 41 can be carried out
continuously by the same process, enabling a reduction in the
process time.
Because the machined depth (D) is set to satisfy the expression
D=R-(R-.delta.)/2.sup.1/2, the insulation coating 41 on the corner
portions can be reliably removed and at the same time the
occurrence of welding defects due to excessive machining can be
suppressed.
Furthermore, in a rear-end coil end group 16a, the free end
portions 50c of the coil segments 50 are disposed so as to line up
in one row radially within each slot with the longitudinal
directions (width directions) of the cross sections thereof
aligned, and because the free end portions 50c (weld portions 45)
of the U-shaped coil segments 50 are formed to be narrow, a
predetermined spacing is formed between the free end portions 50c
of the coil segments 50, ensuring adequate welding space.
Thus, when the free end portions 50c of the two coil segments 50 on
the inner circumferential side are being welded, for example, the
heat from welding is not easily transmitted to the free end
portions 50c of the coil segments 50 on the outer circumferential
side, thereby suppressing accidental welding to the free end
portions 50c on the outer circumferential side and improving
productivity.
Because the free end portions 50c being joined are sufficiently
fused, weld surface area can be ensured. In addition, because the
insulation coating 41 is removed from the free end portions 50c
being joined, there is no deterioration in welding as a result of
unremoved insulation coating. Thus, ample weld strength is obtained
and dislodgment of the joint portions due to vibrations from the
engine can be prevented, improving reliability. Furthermore, the
electric resistance of the joint portions is reduced, enabling the
amount of heat generated by the output current during power
generation to be suppressed, thereby preventing drops in output due
to temperature increases.
In addition, because the volume of the portions to which heat is
applied during welding is reduced, welding time is reduced,
enabling weld beads formed on the joint portions to be reduced. As
a result, spacing is ensured between the inner circumferential
joint portions 51 and the outer circumferential joint portions 52,
suppressing the occurrence of layer shorting due to vibrations and
thereby improving reliability.
Moreover, in Embodiment 1 above, the four free end portions 50c
which align radially are clamped together in clamping jigs 27, the
two free end portions 50c on the inner circumferential side are
welded together, and the two free end portions 50c on the outer
circumferential side are welded together, but the four free end
portions 50c which align radially may also be damped into the
clamping jigs 27 two at a time and welded. That is to say, the two
free end portions 50c on the inner circumferential side are clamped
in the clamping jigs 27 and welded, then the two free end portions
50c on the outer circumferential side are damped in the clamping
jigs 27 and welded.
Embodiment 2
FIG. 15 is a perspective showing width-reduced portions formed in a
wire material in a method for manufacturing a stator for an
alternator according to Embodiment 2 of the present invention, FIG.
16 is a cross section taken along line XVI--XVI in FIG. 15, and
FIG. 17 is a perspective showing width-reduced portions of wire
material with insulation coating removed in a method for
manufacturing a stator for an alternator according to Embodiment 2
of the present invention.
Embodiment 2 is constructed similarly to Embodiment 1 above except
for the fact that width-reduced portions 43A are formed in the wire
material 40 using a press-cutting method instead of a machining
process.
As shown in FIGS. 15 and 16, in Embodiment 2, the width-reduced
portions 43A are formed by cutting the electrical conductor 39 on
both sides of the wire material 40 together with the insulation
coating 41 in the width direction over a predetermined range in the
longitudinal direction at predetermined distances using the
press-cutting method.
Then, the insulation coating 41 is removed by applying a machining
process to the upper and lower surfaces (both surfaces in the
thickness direction) of the width-reduced portions 43A of the wire
material 40.
Thus, the wire material 40 obtained has reduced outer portions 42A
with the insulation coating 41 removed as shown in FIG. 17.
The wire material 40 prepared in this manner is cut at the
longitudinal center of each of the reduced outer portions 42A to
obtain coil members having weld portions at both ends in which the
width and thickness profile is reduced, and the insulation coating
41 has been removed, as in Embodiment 1 above. Then, as in
Embodiment 1 above, generally U-shaped coil segments prepared by
applying a bending process to the coil members are installed in the
stator core to make the stator.
Thus, because Embodiment 2 is constructed similarly to Embodiment 1
except for the fact that the width-reduced portions 43A are formed
by a press-cutting method, the same effects can be obtained as in
Embodiment 1.
Furthermore, according to Embodiment 2, because a press-cutting
method, which is simpler than a machining process, is used to form
the width-reduced portions 43A, productivity is improved compared
to Embodiment 1
Embodiment 3
In Embodiments 1 and 2 above, the insulation coating 41 was removed
by applying a machining process to the upper and lower surfaces of
the width-reduced portions formed at predetermined distances along
the wire material 40, but in Embodiment 3, the insulation coating
41 is burned by directing a flame onto the width-reduced portions
of the wire material 40, and then carbides formed by burning the
insulation coating 41 are removed by brushing.
According to Embodiment 3, because the insulation coating 41 is
burned by a flame, the insulation coating can be removed simply and
reliably without contact. Thus, unremoved insulation coating is
eliminated from the weld portions, preventing in advance poor
weldability as a result of such remnants.
Embodiment 4
In Embodiment 3 above, the insulation coating 41 is burned by
directing a flame onto the width-reduced portions of the wire
material 40, and then carbides formed by burning the insulation
coating 41 are removed by brushing, but in Embodiment 4, the
insulation coating 41 is removed by burning it off with a laser
focused on the width-reduced portions of the wire material 40.
According to Embodiment 4, because the insulation coating 41 is
removed by irradiating it with a laser, carbides from the
insulation coating 41 such as those in Embodiment 3 above are not
left on the laser-irradiated portions. Thus, the need for a step to
remove the carbides by brushing is eliminated, allowing the process
to be abbreviated.
Embodiment 5
In Embodiment 3 above, the insulation coating 41 is burned by
directing a flame onto the width-reduced portions of the wire
material 40, and then carbides formed by the burning of the
insulation coating 41 are removed by brushing, but in Embodiment 5,
masking is applied to the wire material 40 so as to expose the
reduced-width portions, and the insulation coating 41 is dissolved
away by immersing the wire material 40 in a solvent of caustic soda
(sodium hydroxide) or caustic potash (potassium hydroxide).
According to Embodiment 5, because the insulation coating 41 can be
dissolved away by immersing the reduced-width portions of the wire
material 40 in the solvent, the insulation coating 41 of the
reduced-width portions can be reliably removed.
Here, after preparing the coil members by cutting the wire material
40 formed with the reduced-width portions into predetermined
lengths, a large number of the coil members may be bundled and the
insulation coating 41 of the reduced-width portions thereof may be
dissolved away by immersing those reduced-width portions in a
solvent. In that case, because the insulation coating 41 is removed
from a large number of the reduced-width portions of the coil
members together, the insulation coating removal process can be
shortened.
Embodiment 6
In Embodiment 6, the region where each width-reduced portion is to
be formed on the wire material 40 is rolled before cutting and
removing the electrical conductor 39 on both sides of the wire
material 40 in the width direction by a press-cutting process.
Moreover, Embodiment 6 is the same as Embodiment 2 except for the
fact that the rolling process is applied before forming the
width-reduced portion.
The characteristics of Embodiment 6 will now be explained with
reference to FIGS. 18 to 21.
First, as shown in FIGS. 18 and 19, thickness-reduced portions 46
are formed by rolling the wire material 40 over a predetermined
range in the longitudinal direction at predetermined distances
along the wire material 40.
Then, as shown in FIGS. 20 and 21, width-reduced portions 43B are
formed by cutting and removing the electrical conductor 39 on both
sides of the wire material 40 in the width direction together with
the insulation coating 41 over a predetermined range in the
longitudinal direction at predetermined distances using a
press-cutting method.
As in Embodiment 2, reduced outer portions are formed in the wire
material 40 prepared in this manner by removing the insulation
coating 41 from the reduced-width portions 43B, and the coil
members are obtained by cutting the wire material 40 at the
longitudinal centers of the reduced outer portions. The coil
members are bent to form the generally U-shaped coil segments, and
the coil segments are installed in the stator core to make a
stator.
According to Embodiment 6, because the rolling process for the wire
material 40 is introduced before the process for forming the
reduced-width portions 43B, the cross-sectional area of the coil
presented to the cutter is bigger in the process of forming the
width-reduced portions by the press-cutting method, enabling the
wire material 40 to be reliably press cut. Furthermore, because the
free end portions of the coil segments become thinner, the
insertion of the coil into the slots 15b is improved.
Embodiment 7
As shown in FIG. 22, in Embodiment 7, width-reduced portions 43C
are formed by cutting and removing thickness-reduced portions of
the wire material 40 by a press-cutting process such that
longitudinally central portions thereof become slender. Then,
reduced outer portions are formed by removing the insulation
coating 41 from the width-reduced portions 43C, and coil members
are prepared by cutting the wire material 40 at a longitudinally
central portion of each of the reduced outer portions.
Embodiment 7 is the same as Embodiment 6 except for the fact that
the longitudinally central portions of the thickness-reduced
portions are press cut so as to be slender.
According to Embodiment 7, because the width-reduced portions 43C
are formed by cutting and removing such that the longitudinally
central portions of the thickness-reduced portions of the wire
material 40 are made slender, the weld portions at both ends of the
coil members which are prepared by cutting the wire material 40 at
longitudinally central portions of the reduced outer portions have
a tapered shape. Thus, the insertion of the coil segments into the
slots 15b is improved, and the arc can be concentrated on the tips
of the weld portions during welding, further improving
weldability.
Embodiment 8
As shown in FIGS. 23 and 24, in Embodiment 8, width-reduced
portions 43D having a circular cross section are formed by
squeezing the wire material 40 over a predetermined range in the
longitudinal direction at predetermined distances along the wire
material 40 using a press. Then, as shown in FIG. 25, a reduced
outer portion is formed by removing the insulation coating 41 from
the width-reduced portions 43D of the wire material 40 by
positioning three machine tools 55 so as to surround the
width-reduced portions 43D, turning the machine tools 55, and
rotating the three machine tools together around the width-reduced
portion 43D.
According to Embodiment 8, because the width-reduced portions 43D
are formed with a circular cross section, the insulation coating 41
can also be removed completely using machine tools 55, preventing
deterioration in welding caused by unremoved insulation
coating.
Embodiment 9
In Embodiment 9, after removal of the insulation coating 41 from
the width-reduced portions 43D by the machine tools 55 shown in
Embodiment 8, a rolling process is added for forming reduced outer
portions 42E having a rectangular cross section by rolling the
width-reduced portions 43D.
According to Embodiment 9, because reduced outer portions 42E
having a rectangular cross section are obtained as shown in FIGS.
26 and 27, the contact surface area between weld portions being
joined to each other is increased, enabling joint strength to be
increased. Thus, dislodgment of the joint portions due to
vibrations from the vehicle or from the engine can be
prevented.
Embodiment 10
As shown in FIG. 28, in Embodiment 10, after forming coil members
44A by cutting the wire material 40 at longitudinally central
portions of the reduced outer portions, weld portions 45A at both
ends of the coil members 44A are fused by heating.
Moreover, Embodiment 10 is constructed in the same way as
Embodiment 2 above except for the fact that the weld portions 45A
at both ends of the coil members 44A are fused by heating.
According to Embodiment 10, because the weld portions 45A at both
ends of the coil members 44A are fused by heating, corner portions
of the weld portions 45A are fused into a smooth profile. Thus, any
bulges and burrs which form on side portions of the cut surfaces of
the reduced outer portions when the coil members 44A are formed by
cutting the wire material 40 at the longitudinally central portions
of the reduced outer portions are eliminated, thereby improving
insertion of the coil segments into the slots.
Thus, the same effect can be achieved by heat fusing the free end
portions at both ends of the coil segments after the coil segments
have been formed from the coil members.
Embodiment 11
Embodiments 1 to 10 above apply to a stator coil prepared using
coil segments 50 obtained by bending short coil members into a
general U shape, but Embodiment 11 applies to a stator coil
prepared using long coil wires obtained by bending long coil
members into a wave shape.
First, the winding construction of one stator winding phase group
will be explained in detail with reference to FIG. 29. Moreover, in
FIG. 29, the wiring at a first axial end of the stator core is
represented by solid lines and the wiring at a second axial end of
the stator core is represented by dotted lines. Furthermore, a
stator core 62 is formed into a cylindrical shape, a number of
teeth 62a having a generally rectilinear cross section being
disposed at even pitch in a circumferential direction so as to
protrude radially inwards and slots 62b for housing the coil being
formed between the teeth 62a. The grooves of each of the slots 62b
are parallel to an axial direction, and open to an inner
circumferential side. In this stator core 62, ninety-six slots 62b
are formed so as to house two three-phase stator windings 64 which
will be described below such that the number of slots housing each
winding phase group corresponds to the number of magnetic poles
(sixteen) in the rotor, the number of slots being two per phase per
pole.
One stator winding phase group 65 is constituted by first to fourth
winding sub-portions 71 to 74 functioning as coil wires in each of
which one coil member 70 is formed into a wave shape. The first
winding sub-portion 71 is constructed by wave winding one coil
member 70 into every sixth slot from slot numbers 1 to 91 so as to
alternately occupy a first position from an inner circumferential
side (first address) and a second position from the inner
circumferential side (second address) inside the slots 62b. The
second winding sub-portion 72 is constructed by wave winding a coil
member 70 into every sixth slot from slot numbers 1 to 91 so as to
alternately occupy the second address and the first address inside
the slots 62b. The third winding sub-portion 73 is constructed by
wave winding a coil member 70 into every sixth slot from slot
numbers 1 to 91 so as to alternately occupy a third position from
the inner circumferential side (third address) and a fourth
position from the inner circumferential side (fourth address)
inside the slots 62b. The fourth winding sub-portion 74 is
constructed by wave winding a coil member 70 into every sixth slot
from slot numbers 1 to 91 so as to alternately occupy the fourth
address and the third address inside the slots 62b.
Then, at the first end of the stator core 62, a first end portion
72a of the second winding sub-portion 72 extending outwards from
the second address of slot number 1 is joined to a second end
portion 72b of the second winding sub-portion 72 extending outwards
from the first address of slot number 91 to form a winding
sub-portion having one turn, and in addition, a first end portion
74a of the fourth winding group 74 extending outwards from the
fourth address of slot number 1 is joined to a second end portion
74b of the fourth winding group 74 extending outwards from the
third address of slot number 91 to form a winding sub-portion
having one turn.
Furthermore, at the second end of the stator core 62, a first end
portion 71a of the first winding sub-portion 71 extending outwards
from the first address of slot number 1 is joined to a second end
portion 71b of the first winding sub-portion 71 extending outwards
from the second address of slot number 91 to form a winding
sub-portion having one turn, and in addition, a first end portion
73a of the third winding group 73 extending outwards from the third
address of slot number 1 is joined to a second end portion 73b of
the third winding group 73 extending outwards from the fourth
address of slot number 91 to form a winding sub-portion having one
turn.
Thus, each of the first to fourth winding sub-portions 71 to 74
constitutes a winding sub-portion having one turn in which one coil
member 70 is wound into every sixth slot 62b so as to alternately
occupy an inner and an outer layer in a slot depth direction.
Within each of the slots 62b, the coil members 70 are arranged to
line up in a row of four radially by radially aligning the
longitudinal direction of the flat cross sections (rectilinear
cross sections) of the coil members 70.
Next, a portion of the coil member 70 of the first winding
subportion 71 extending outwards from the first address of slot
number 61 and the second address of slot number 67 at the first
axial end of the stator core 62 is cut, and a portion of the coil
member 70 of the third winding subportion 73 extending outwards
from the third address of slot number 61 and the fourth address of
slot number 67 at the first axial end of the stator core 62 is also
cut. In addition, a portion of the coil member 70 of the second
winding sub-portion 72 extending outwards from the first address of
slot number 67 and the second address of slot number 73 at the
first axial end of the stator core 62 is cut, and a portion of the
coil member 70 of the fourth winding sub-portion 74 extending
outwards from the third address of slot number 67 and the fourth
address of slot number 73 at the first axial end of the stator core
62 is also cut.
Then, the first cut end 71c of the first winding sub-portion 71 is
joined to the first cut end 72c of the second winding sub-portion
72, the first cut end 73c of the third winding sub-portion 73 is
joined to the second cut end 71d of the first winding sub-portion
71, the first cut end 74c of the fourth winding sub-portion 74 is
joined to the second cut end 72d of the second winding sub-portion
72, to form one stator winding phase group 65 having four turns
constructed by connecting the first to fourth winding subportions
71 to 74 in series.
Moreover, the joint portion between the first cut end 71c of the
first winding sub-portion 71 and the first cut end 72c of the
second winding sub-portion 72, the joint portion between the first
cut end 73c of the third winding sub-portion 73 and the second cut
end 71d of the first winding sub-portion 71, and the joint portion
between the first cut end 74c of the fourth winding sub-portion 74
and the second cut end 72d of the second winding sub-portion 72
become crossover connection portions, the second cut end 73d of the
third winding sub-portion 73 and the second cut end 74d of the
fourth winding sub-portion 74 become a neutral point (N) and an
output wire (O), respectively.
A total of six stator winding phase groups 65 are similarly formed
by offsetting the slots 62b into which the first to fourth winding
sub-portions 71 to 74 are wound one slot at a time. Then, as shown
in FIG. 30, three stator winding phase groups 65 are connected into
each of two Y connections to form a stator coil 63 which is
composed of two three-phase stator windings 64, each of the
three-phase stator windings 64 being connected to its own rectifier
12. Each rectifier 12 is connected in parallel so that the
direct-current output from each is combined.
Thus, each of the coil members 70 constituting the first to fourth
winding sub-portions 71 to 74 is wound into a wave winding so as to
extend outwards from first slots 62b at axial ends of the stator
core 62, fold back, and enter second slots 62b six slots away. Each
coil member 70 is wound so as to alternately occupy an inner layer
and an outer layer in a slot depth direction (radially) in every
sixth slot. The first winding sub-portion 71 and the second winding
sub-portion 72 are offset by an electrical angle of 180.degree. so
as to be inversely wound relative to each other. Similarly, the
third winding sub-portion 73 and the fourth winding sub-portion 74
are also are offset by an electrical angle of 180.degree. so as to
be inversely wound relative to each other.
Turn portions 81a of the coil members 70 extend outwards from axial
end surfaces of the stator core 62 and fold back to form coil ends.
Thus, at both axial ends of the stator core 62, the turn portions,
which are formed with a substantially identical shape, are
separated from each other both circumferentially and radially and
are arranged neatly into two rows circumferentially to form
front-end and rear-end coil end groups.
Next, the assembly of a stator 60A will be explained in detail with
reference to FIGS. 1 to 4 and FIGS. 31 to 37.
First, as shown in FIGS. 1 and 2, a wire material 40 is prepared by
coating a flat electrical conductor 39 made of copper or the like
having a rectangular cross section with an insulation coating 41.
Then, both surfaces in a width direction and both surfaces in a
thickness direction of the wire material 40 are machined down to
the machined depth (D) over a predetermined range in a longitudinal
direction at predetermined distances along the wire material 40.
Thus, a portion of each side of the electrical conductor 39 of wire
material 40 in the width direction and in the thickness direction
is removed together with the insulation coating 41 to obtain
reduced outer portions 42 as shown in FIGS. 3 and 4. Next, the long
coil members 70 are prepared by cutting the wire material 40 at
longitudinally central portions of the reduced outer portions 42.
At this time, as shown in FIG. 31, the width and thickness of both
ends of the coil members 70 are reduced.
As shown in FIG. 31, twelve coil members 70 prepared in this manner
are simultaneously bent in the same plane to form a lightning-bolt
shape. Then, a winding assembly 80, shown in FIGS. 33A and 33B, is
prepared by progressively folding the coil members 70 at right
angles, as indicated by the arrow in FIG. 32, using a jig.
Moreover, each of the coil members 70 is bent to form a coil wire
81 in a wave-shaped pattern in which straight portions 81b
connected by the turn portions 81a are arranged at a pitch of six
slots (6P), as shown in FIG. 34. Adjacent straight portions 81b are
offset by a distance equal to one width (W) of the coil members 70
by means of the turn portions 81a. The winding assembly 80 is
constructed by arranging six coil-wire pairs so as to be offset by
a pitch of one slot from each other, each coil-wire pair consisting
of two coil wires 81 formed in the above wave-shaped pattern which
are offset by a pitch of six slots and arranged such that the
straight portions 81b overlap as shown in FIG. 35. Six end portions
of the coil wires 81 each extend outwards from first and second
sides at first and second ends of the winding assembly 80.
Furthermore, the turn portions 8la constituting the coil ends are
arranged so as to line up neatly in rows on first and second side
portions of the winding assembly 80. Here, each of the coil wires
81 corresponds to one of the first to fourth winding subportions 71
to 74 shown in FIG. 38.
A parallelepiped laminated core 83 is prepared as shown in FIG. 36
by laminating a predetermined number of sheets of SPCC material,
which is a magnetic material, formed with trapezoidal slots 83a at
a predetermined pitch (an electrical angle of 30.degree.) and laser
welding an outer portion thereof
Then, as shown in FIG. 37A, insulators 19 are mounted in the slots
83a of the parallelepiped laminated core 83, and the straight
portions 81b of two winding assemblies 80 are inserted so as to
stack up within each of the slots 83a. Thus, the two winding
assemblies 80 are installed in the parallelepiped laminated core 83
as shown in FIG. 37B. The straight portions 81b of the coil wires
81 are housed in lines of four in a radial direction within the
slots 83a and are electrically insulated from the parallelepiped
laminated core 83 by the insulators 19. The two winding assemblies
80 are mounted in the parallelepiped laminated core 83 so as to be
stacked one on top of the other.
Next, the parallelepiped laminated core 83 is rolled up and its end
surfaces are abutted and welded to each other to obtain the
cylindrical stator core 62, as shown in FIG. 37C.
Then, based on the connection method shown in FIG. 38, the stator
winding phase groups 65 are formed by connecting the end portions
of each of the coil wires 81.
Here, burning off the insulation coating 41 by means of irradiation
with a laser is suitable for the removal of the insulation coating
41 from the cut ends of the coil wires 81 used for the crossover
connections, the output wires, and the neutral points.
Thus, according to Embodiment 11, because the reduced outer
portions 42 are formed in the wire material 40 and then the coil
members 70 are obtained by cutting the wire material 40 at the
reduced outer portions 42, the insulation coating 41 is removed
from the end portions of the coil wires 81 which are formed by
bending the coil members 70 into a wave shape, reducing the width
and the thickness thereof.
Furthermore, the first to fourth winding sub-portions 71 to 74
constituting one stator winding phase group 65 are each formed into
a winding having one turn by welding together the end portions
thereof. At that time, the end portions 71a, 71b, 73a, and 73b of
the first and third winding sub-portions 71 and 73 are arranged at
the second end of the stator core 62 so as to line up in one row
radially with the longitudinal direction of the cross sections
(width directions) thereof aligned radially, and the end portions
72a, 72b, 74a, and 74b of the second and fourth winding subportions
72 and 74 are arranged at the first end of the stator core 62 so as
to line up in one row radially with the longitudinal direction of
the cross sections (width directions) thereof aligned radially.
Because the width of the coil wires 81, that is to say, the width
of each of the end portions of the first to the fourth winding
sub-portions, is reduced, predetermined spacing is formed between
the end portions 71a and 71b and the end portions 73a and 73b, and
similarly between the end portions 72a and 72b and the end portions
74a and 74b, ensuring welding space.
Consequently, the same effects can also be obtained in Embodiment
11 as in Embodiment 1 above.
Furthermore, in Embodiment 11, because each of the winding
subportions having one turn is formed from one coil wire 81, the
number of joints can be significantly reduced compared to
Embodiments 1 to 10 above in which each of the winding sub-portions
having one turn is formed from a large number of the U-shaped
segments 50 connected in series, enabling the productivity of the
stator to be improved, eliminating softening of the electrical
conductor due to welding, increasing the rigidity of the stator,
and enabling magnetic noise to be reduced.
Furthermore, because the coil end groups are constituted by the
turn portions 81a of the coil wires 81, coil end height can be
reduced compared to Embodiments 1 to 10 above in which the coil end
groups are constituted by welding together the free end portions
50c of the coil segments 50. Thus, wind resistance in the coil end
groups is reduced, enabling the reduction of wind noise due to the
rotation of the rotor 7, and coil leakage reactance is also
reduced, improving output and efficiency.
In addition, because the winding assembly 80 is formed from twelve
coil wires 81, six stator winding phase groups 65 are wound by
installing two winding assemblies 80 into the stator core 62 in two
rows, enabling assembly to be significantly improved.
Moreover, in each of the above embodiments, the width-reduced
portions are formed by removing the electrical conductor 39 on both
sides of the wire material 40 in the width direction together with
the insulation coating 41 by means of a machining process or a
press-cutting method, then the reduced outer portions are formed by
removing the insulation coating 41 from the width-reduced portions,
but the reduced outer portions may also be formed by removing the
insulation coating 41 from the wire material 40 over a
predetermined longitudinal range generally centered on each of the
cutting positions. In that case, the outer dimension of the reduced
outer portions is reduced in proportion to the thickness of the
insulation coating 41, reducing problems caused by bulges and burrs
arising on the side portions of the cut surfaces of the reduced
outer portions. Then, when the coil segments or the coil wires
formed from the wire material are mounted into the stator core, end
portions of the coil segments or the coil wires are separated from
each other, ensuring welding space. Moreover, the methods mentioned
in Embodiments 3 to 5, for example, burning away the insulation
coating with a flame, burn away the insulation coating by
irradiating it with a laser, or dissolving away the insulation
coating with a solvent, etc., can be used when removing the
insulation coating 41.
Furthermore, in each of the above embodiments, four straight
portions 50a and 81a of the coil segments 50 or the coil wires 81
are arranged in one row in a radial direction in the each of the
slots 15b and 62b, but the number of straight portions arranged in
the slots is not limited to this number.
The present invention is constructed in the above manner and
exhibits the effects described below.
According to one aspect of the present invention, there is provided
a method for manufacturing a stator for an alternator, the method
including:
forming coil members by cutting wire material into predetermined
lengths, the wire material being composed of an electrical
conductor having a flat cross section coated with an insulation
coating;
forming coil wires of a predetermined shape by subjecting the coil
members to a bending process;
installing a predetermined number of the coil wires into a stator
core; and
forming a winding group having a predetermined number of turns by
welding together end portions of each of the coil wires installed
in the stator core,
the method further including:
forming a reduced outer portion over a predetermined longitudinal
range generally centered on each of the cutting positions on the
wire material, enabling producibility and reliability to be
improved.
The reduced outer portion may be formed by removing the insulation
coating from the wire material over the predetermined longitudinal
range centered on each of the cutting positions, eliminating
deterioration in weldability as a result of unremoved insulation
coating and suppressing the occurrence of weld dislodgement due to
vibration.
Forming the reduced outer portion may include:
forming a width-reduced portion by removing first and second edges
of the electrical conductor in a width direction together with the
insulation coating over a predetermined longitudinal range centered
on each of the cutting positions; and
removing the insulation coating from first and second edges of the
width-reduced portion in a thickness direction, ensuring welding
space when welding together the end portions of the coil wires, and
reducing the surface area of the width-reduced portions from which
the insulation coating is removed, thereby shortening the time
required for the process of removing the insulation coating.
The width-reduced portion may be formed by cutting away the first
and second edges of the electrical conductor in the width direction
together with the insulation coating by a machining process,
reducing the surface area of the width-reduced portions from which
the insulation coating is removed, and thereby shortening the time
required for the process of removing the insulation coating.
The width-reduced portion may be formed by cutting off the first
and second edges of the electrical conductor in the width direction
together with the insulation coating using a press-cutting method,
enabling the width-reduced portion to be prepared easily.
The width-reduced portion may be formed by:
forming a thickness-reduced portion over a predetermined
longitudinal range centered on each of the cutting positions by
rolling the wire material; and then
cutting off the first and second edges of the electrical conductor
in the width direction together with the insulation coating at the
thickness-reduced portion using a press-cutting method, improving
insertion of the coil wires into the slots.
The width-reduced portion may be formed into a shape having a cross
section tapering towards a central portion from first and second
longitudinal ends, enabling concentration of an arc on the weld
portions at the time of welding, thereby increasing weldability and
improving weld strength.
The width-reduced portion may be formed by forming the wire
material into a round shape of circular cross section over a
predetermined longitudinal range centered on each of the cutting
positions; and then
the insulation coating of the width-reduced portion may be removed
by mechanical stripping, enabling the insulation coating to be
reliably removed even if a mechanical tool is used, thereby
preventing deterioration in weldability as a result of unremoved
insulation coating.
The width-reduced portion from which the insulation coating has
been mechanically stripped may be formed into a flat shape,
improving insertion of the coil wires into the slots.
The insulation coating on the reduced outer portion may be removed
by a machining process, enabling the insulation coating to be
reliably removed, thereby preventing deterioration in weldability
as a result of unremoved insulation coating.
The insulation coating on the reduced outer portions may be burned
away by a flame and then carbides formed thereby may be removed by
brushing, shortening the time required for the process of removing
the insulation coating.
The insulation coating on the reduced outer portion may be removed
by burning away by means of irradiation with a laser, making the
brushing process unnecessary, thereby shortening the time required
for the process of removing the insulation coating.
The insulation coating on the reduced outer portion may be removed
by rinsing with a solvent, enabling the insulation coating to be
reliably removed, thereby preventing deterioration in weldability
as a result of unremoved insulation coating.
A smooth tip shape may be formed by melting corner portions of
first and second ends of the coil members or comer portions of the
coil wires, improving insertion of the coil wires into the
slots.
The coil wires may be formed in a general U shape composed of a
pair of straight portions separated by a predetermined number of
slots being connected by a turn portion having a general V shape,
enabling the stator coil to be prepared by preparing the
cylindrical stator core and then inserting the coil wires into the
stator core, facilitating the manufacturing of the stator.
The coil wires may be formed into a wave-shaped continuous wire in
which straight portions are arranged at a predetermined slot pitch
and end portions of adjacent straight portions may be connected to
each other by generally V-shaped turn portions, whereby the number
of joints is significantly reduced, facilitating the process of
installing the coil wires in the stator core and thereby improving
productivity, and making the coil ends into continuous-wire turn
portions, thereby lowering the axial height of the coil end
groups.
According to the present invention, there is provided a stator for
an alternator, the stator including:
a cylindrical stator core in which a number of slots having grooves
aligned axially are disposed parallel to each other
circumferentially so as to be open on an inner circumferential
side; and
a stator coil constructed by welding together a number of end
portions of coil wires having a flat cross section coated with an
insulation coating, the stator coil being wound so as to fold back
outside the slots at axial end surfaces of the stator core so as to
alternately occupy an inner and an outer layer in a slot depth
direction within the slots at intervals of a predetermined number
of slots,
wherein an outer dimension of each of the end portions of the coil
wires is reduced compared to other portions of the coil winding,
providing superior reliability by ensuring welding space when
welding together the end portions of the coil wires, increasing the
weld strength in the joint portions between the end portions of the
coil wires, and suppressing dislodgement of the joint portions due
to vibration, and at the same time, reducing the electrical
resistance of the joint portions, lowering the amount of heat
generated by the output current during power generation and
suppressing reductions in output as a result of temperature
increases.
The end portions of the coil wires may be formed such that a width
dimension of the end portion of the coil wires is narrower than
other portions of the coil wires, and the insulation coating may be
removed from the end portions, reliably ensuring welding space when
welding together the end portions of the coil wires, and
suppressing deterioration in weldability as a result of unremoved
insulation coating.
The insulation coating may be removed from the end portions of the
coil wires, suppressing deterioration in weldability as a result of
unremoved insulation coating.
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